This invention deals generally with infrared sensors and more specifically with a miniaturized assembly which detects very low power infrared radiation and converts it into a usable electrical signal.
Low power infrared radiation is very difficult to detect and use electronically because sensitive photodetectors, such as photomultiplier and image intensifier tubes, which convert radiation into electrical signals, have very low sensitivity in the infrared region of the spectrum.
One technique which has been used to overcome this low infrared sensitivity has been the use of special phosphor materials external to the photosensitive tubes. Such materials upconvert, that is, they generate higher frequency and shorter wavelength radiation when stimulated by the infrared radiation, and the higher frequency radiation can then be accommodated by conventional photodetectors. U.S. Pat. Nos. 4,891,507 and 5,012,098 to Lindmayer disclose devices using such phosphors.
U.S. Pat. No. 4,980,566 to Heilweil discloses the use of solid-state nonlinear conversion crystals within an infrared spectrometer, describes what is essentially a table top configuration, and specifies one meter distances within the apparatus.
U.S. Pat. No. 5,946,093 to DeFreez et al describes a particle detection system that uses a solid state lasant in the form of crystal or glass as an upconversion laser. The apparatus apparently has significant dimensions since it includes a volume to contain flowing streams of fluid.
It would be very beneficial to have available for scientific and commercial use a compact robust infrared sensor that has high sensitivity, low noise, high efficiency, and long life. Even greater benefits would result from low manufacturing costs and no need for cryogenic cooling.